Certain refrigerator appliances include a dispensing assembly for dispensing ice and/or liquid water. Such dispensing assemblies generally include an actuator, such as a button or paddle, or a sensor assembly, such as an ultrasonic sensor assembly, for initiating a flow of ice and/or liquid water into a dispenser recess of the dispensing assembly. By pressing the actuator or triggering the sensor, a user can initiate the flow of ice and/or liquid water into a container, such as a cup or pitcher, positioned within the dispenser recess.
Certain dispensing assemblies having ultrasonic sensors also include features for automatically filling the container with ice and/or liquid water. The ultrasonic sensor can be operated to monitor a level of ice and/or liquid water within the container, and the dispensing assembly can terminate the flow of ice and/or liquid water into the container when the container is full or at a predetermined level. For such auto-fill features to operate properly, the ultrasonic sensor measures the container and its contents accurately and precisely. In particular, ultrasonic sensors can measure various parameters of the container in order to automatically fill the container with ice and/or liquid water. Such parameters can include an alignment of the container, a location of a container lip, a location of a container bottom, and a height of liquid water and/or ice within the container relative to the container lip or container bottom.
However, ultrasonic sensors can have difficulty accurately and precisely measuring such parameters. In particular, under certain usage conditions, ultrasonic sensors can become contaminated with foreign material including, but not limited to, colas, juices, food particles, or other contaminants or pollutants. For example, such contaminants can become affixed to or otherwise impair or inhibit proper operation of the ultrasonic sensor assembly.
Operation of the ultrasonic sensor assembly while in a contaminated state (i.e. with substantial contaminants present) can result in decreased performance. For example, a contaminated ultrasonic sensor assembly may exhibit increased detection of false positives, failure to detect an object at all, or other improper operations.
In turn, such difficulty can lead to user frustration and dissatisfaction because the automatic fill process may not operate properly due to unacceptable measurements from the ultrasonic sensor assembly. For example, in the context of auto-fill features in a refrigerator, false positives can fool the dispensing assembly into believing that a larger container is present than there actually is, and therefore lead to over-fills and spillage. As another example, false positives may result in the dispensing assembly believing a container to be completely filled with ice or liquid, when in fact it remains empty.
Therefore, improved systems and methods for detecting a contamination status of an ultrasonic sensor assembly included in a refrigeration appliance are desirable.